Incinerator having improved scrubber



June 3, 1969 L. H. ANDERSEN INCINERATOR HAVING IMPROVED SCRUBBER FiledDec. 18, 1967 Sheet of 7 June 3, 1969 L. H. ANDERSEN INCINERATOR HAVINGIMPROVED SCRUBBER Filed Dec. 18, 19s? B Zea/er @Zfcflnderaen H II V,

June 3, 1969 L. H. ANDERSEN INCINERATOR HAVING IMPROVED SCRUBBER SheetFiled Dec. 18. 1967 fiflnzorr [es/er 4/5. M72 dersen June 3, 1969 L, H.ANDERSEN 7, 87

INGINERATOR HAVING IMPROVED SCRUBBER Filed Dec. 18, 1967 Sheet 4 of '7June 3, 1969 L. H. ANDERSEN I 3,447,237.

INCINERATOR HAVING IMPROVED SCRUBBER Filed Dec. 18, 1967 Sheet 5' of 7li'n/niorf [es/er d. %7zder.sen

June 3, 1969 1., H. ANDERSEN INCINERATOR HAVING IMPROVED SCRUBBER FiledD80. 18, 1967 June 3, 1969 L, H. ANDERSEN INCINERATOR HAVING IMPROVEDSCRUBBER Sheet Filed Dec. 18, 1967 s s\\\\\\\ F [aszer c ZZ finders enUnited States Patent US. C]. 55-85 19 Claims ABSTRACT OF THE DISCLOSUREThe specification discloses scrubber and dryer apparatus particularlyuseful in conjunction with municipal incinerators for the removal of flyash from the gaseous combustion products. The scrubber comprises achamber having surface-porous castable refractory piers in several rows,each row of which is staggered with respect to the preceding row. In oneembodiment, the chamber widens from front to rear and the spacingbetween adjacent piers in each succeeding row decreases. The ash istrapped by impingement on a continuous curtain of water disposed at theinlet of the scrubber just upstream of the piers. Water to form thecurtain is pumped into a manifold set transverse to the chamber inletand having a slot therein. The gases carry the water downstream inrelatively large droplets to impinge on the piers where the water andtrapped ash flows off. The dryer chamber comprises a deflecting archhaving openings therein that directs the gases against the chamber wallswhereby water is stripped therefrom. The gases, after passing throughthe scrubber and then the dryer, are exhausted as substantially clearair, having a tested dust loading value of from 54 to 68% below thecommonly accepted standard of 0.85 lb. dust/ 1000 lbs. flue gas. Thescrubber and dryer can be used for other gases, e.g. for trapping S0 inthe production of sulfuric acid. A method of scrubbing gases isdisclosed.

This application is a continuation-in-part of application Ser. No.527,368 filed Feb. 14, 1966, and now abandoned.

Field This invention relates to a scrubber-dryer device for industrialgases, and more particularly to a scrubber-dryer in combination with anincinerator that significantly reduces air pollution. The application isalso directed to a method of treating gases such as a result fromincineration of household and industrial waste, garbage and the likewhich results in relatively clean products of combustion beingdischarged from the incinerator as compared with the discharge fromconventional chimney or stack-type refuse burners by reason of theremoval of a greater proportion of fly ash.

Background Spray chambers and conventional gas scrubbers have long beenused in combination with incinerators and the like in order to wash thegases and remove fly ash therefrom in an attempt to prevent pollution ofthe air by the exhaust discharge from such incinerators. A typicalmunicipal incinerator of the above type is illustrated in US. Patent3,031,981 wherein a spray chamber is used to trap the fly ash beforeexhausting to the atmosphere. The typical plant has a primary combustionchamber, a secondary chamber that ordinarily operates both as a fly ashsettling chamber and a secondary combustion zone, a spray chamber incommunication therewith and an exhaust stack. However, actual experiencehas shown that spray chambers have not been satisfactory in reducing theallowable dust loading of the flue gas to an acceptable "Ice level. Inview of the recent emphasis on stricter air pollution codes, suchoperation has become entirely unacceptable.

There are many different codes and limitations on solids emissions beingenforced by air pollution agencies throughout the country. The one thathas received the widest acceptance up to this time has limited thepermissible discharge from incinerators to 0.85 lb. dust per 1000 lbs.flue gas, adjusted to a 50% excess air basis. The second most widelyadopted and enforced limitation uses the same dust concentrationlimitation, but the results are corrected to a 12% carbon dioxide basis.Both of these limitations have their origin in the old Model Smoke Lawof the American Society of Mechanical Engineers. In recent years, therehas been a definite trend to reduce the permissible level of incineratorparticulate emission. Unfortunately, however, there has been littleuniformity followed in the method of expressing these limitations aseach new code is adopted, and thus incinerators to be nationallyacceptable must meet the most stringent code. In test runs onincinerators embodying the scrubber and dryer of this invention, theaverage of several runs of exit dust loading is between 53.4% and 68.0%below the above-noted most widely accepted exit flue gas dust loadinglimitation of 0.85 lb. of dust per 1000 lbs. of flue gas, corrected to a50% excess air basis. In addition, actual test runs show that anincinerator embodying the scrubber and dryer of the present inventionachieves even the most stringent requirements (e.g., city of Detroit andState of Florida) for stack exit dust loading, whether expressed inactual gas basis or the less commonly used dry standard cubic foot perminute basis, either corrected to 50% excess air or 12% carbon dioxideand expressed in grains per dry cubic foot or pounds of dust per 1000lbs. of flue gas.

Conventional multi-wash collectors have been used in combination withincinerators to remove fly ash. Such multi-wash collectors operate byintroducing, under force draft, dust, fumes or vapors tangentiallythrough an inlet at the bottom of the silo. A conical bottom creates avortex which sends the air upwards in a spiraling motion. A washingagent, such as water, is introduced at no head pressure just below anentrainment separator, and the water cascades downwardly evenly overplates carrying collected material to a slurry outlet. Another type of acascade collector is shown in US. Patent 2,585,440. It differsprincipally from the above multi-wash collector by being of thedowndraft type with sprayers above the series of balfles.

However, actual experience shows that such types of cascade collectorshave not been satisfactory in reducing incinerator flue gases topermissible levels of dust loading. One of the problems is that the fluegases contain acid forming components which in combination with thewater form extremely corrosive conditions that destroy the metalcomponents of such type of collectors. In order to overcome thisproblem, lime has been added to the water used in such collectors inorder to neutralize the acids formed. However, under conditionsinvolving hot gases of up to 1400 to 1800 F. exiting from the primary orsecondary chamber of incinerators, the quantities of lime in the waternecessary to neutralize the acid components is such that rapid build-upof a deposit on the cascade surfaces, entrainment separators and platesclogs the scrubber to the point of inoperability. The lifetime of suchseparators is also extremely short and thus economically unfeasible. Inaddition, the spray or cascade type of collector does not remove theentrained particulate matter from the air to the degree necessary tosatisfy minimum requirements for modern day codes.

Typical examples of spray type scrubbers are found in US. Patents2,045,115, 1,952,389, 1,509,475, 3,031,982,

and 2,045,519. Typical problems with such conventional type ofspray-type scrubbers have been that the scrubber heads, although theymay be recessed in the chamber walls, continuously burn out and becomeclogged. In addition, those made of metal suffer from the same shortlifetime problems as described above with reference to the cascade typeof collectors. More seriously, however, is the fact that they do notoperate to produce the necessary result, that of removing the airpollutants to an acceptable level.

THE INVENTION Objects A major object of this invention is to provide animproved type of scrubber and dryer useful for removing entrainedparticulate matter and acid forming components from industrial gases,such as flue gases from incinerators, those involved in the productionof sulphuric acid, or the like, which scrubber and dryer removesentrained particulate matter and undesirable components to a level belowpermissible for discharge to the atmosphere as substantially clear air.

It is another object of this invention to utilize such scrubber anddryer in combination with municipal type incinerators in wihch secondarycombustion chambers may be dispensed with, the construction beingextremely simple, compact and inexpensive and providing substantialimprovements in efficiency whereby the capacity of existing incineratorscan be increased.

One object of the invention is to provide an incinerator having acombustion chamber for refuse which is provided with an inlet for refusedumped from a truck or the like and an outlet leading to a gas scrubberthrough which the products of combustion flow and from which most of thefly ash is removed, the products of combustion then passing through adrying chamber before being discharged to atmosphere.

Another object is to provide an efiicient refuse incinerator which iscomparatively inexpensive to construct and economical to operate, and toprovide a method of treating refuse which burns a maximum proportionthereof and efficiently removes both dry ashes and fly ash from thecombustion chamber before the residual products of combustion aredischarged to atmosphere, the design being such that the usual highstack to create draft is not needed, and improved incinerator capacitymay be achieved.

An additional object is to provide in combination with thescrubber-dryer a single conveyor to receive water drained from scrubberelements in a chamber of the gas scrubber together with fly ashcollected thereby from the products of combustion passing through thegas scrubber and operable to remove sludge from the water whereupon thewater can be reused in the gas scrubber.

Another object is to provide pump means to receive water from the sludgeconveyor and recirculate it to the gas scrubber, the gas scrubber havinga trough receiving such water and provided with a transverse slot at theinlet end of the scrubber chamber from which a curtain of water fallsacross the inlet, and to provide a series of spaced scrubber elementsagainst which such water is carried by the products of combustion asthey pass through the gas scrubber chamber.

Another additional object is to provide the scrubber elements in theform of refractory piers mounted in the gas scrubber chamber, aplurality of rows of the piers being provided and the piers in eachsuccessive row being staggered relative to the piers in the precedingrow, the spacing between the piers being such as to substantiallyincrease the velocity of the products of combustion as they pass throughthe gas scrubber chamber.

Another object is to provide means for supplying makeup water to thepump means to compensate for any water that is evaporated during the gasscrubber operation.

Another object is to provide a drying chamber downstream of the gasscrubber which has deflecting means therein for deflecting the productsof combustion from the gas scrubber toward the wall of the dryingchamber so that any water carried thereby impinges the wall and drainsdown it and into the sludge conveyor instead of passing out toatmosphere.

Drawings With these and other objects in view, my invention consists inthe construction, arrangement and combination of the various parts ofthe scrubber and dryer and their combination with an incinerator, and inthe steps of my method of treating refuse, whereby the objects abovecontemplated are attained, as hereinafter more fully set forth, pointedout in my claims and illustrated in detail on the accompanying drawings,wherein:

FIG. 1 is a plan view of the reciprocating grate means and an ashconveyor of my incinerator which are disclosed and claimed in mycopending application Ser. No. 648,845, filed Nov. 9, 1967, as adivision of parent application Ser. No. 527,368 filed Feb. 14, 1966.

FIG. 1A is a continuation of FIG. 1 and shows a gas scrubber inhorizontal section;

FIG. 2 is a vertical sectional view through the portion of myincinerator shown in FIG. 1, FIG. 1 being taken on the line 11 of FIG.2;

FIG. 2A is a vertical sectional view through the remaining portion of myincinerator and is a continuation of FIG. 2, FIG. 1A being taken on theline 1A--1A of FIG. 2A;

FIG. 3 is a part plan view, part horizontal sectional view taken on theline 3-3 of FIG. 2A;

FIG. 4 is an enlarged horizontal sectional view on the line 44 of FIG.3;

FIG. 5 is a vertical sectional view on the line 55 of FIG. 1, and showsthe parts on an enlarged scale;

FIG. 6 is a further enlarged detail sectional view of the portion ofFIG. 5 shown within the dot-and-dash rectangle 6 thereof;

FIG. 7 is a vertical sectional view on the line 77 of FIG. 1A showingdetails of a dry ash conveyor;

FIG. 8 is a vertical sectional view similar to a portion at the righthand end of FIG. 2 to show further details of the dry ash conveyor;

FIG. 9 is a vertical sectional view on the line 9-9 of FIG. 2 to showdetails of a rack and pinion drive for grate means of my incinerator;

FIG. 10 is a vertical sectional view of a second embodiment of myincinerator;

FIG. 10A is a vertical sectional view of the scrubberdryer section ofthe embodiment shown in FIG. 10 taken along a line 10A10A in FIG. 11;and

FIG. 11 is a plan view of the scrubber-dryer section shown along line1111 of FIG. 10A.

Detailed description On the accompanying drawings of a singleincinerator cell, several areas and dominant parts of the incineratorper se and the scrubber-dryer are designated by reference characters asfollows:

CC-Combustion Chamber GM-Grate Means ACAsh Conveyor GS-Gas ScrubberSCSludge Conveyor DADeflecting Arch DC-Drying Chamber The combustionchamber CC comprises a floor 10 shown in FIGS. 5, 7 and 8, sidewalls 12and a top wall 14. The combustion chamber also has a front wall 16 and arear wall 18, and adjacent the front wall 16 is an inclined wall 20constituting an inlet chute. The combustion chamber is the primarycombustion chamber or first high temperature zone of the incinerator. Asshown in FIG. 2, the left hand end of the combustion chamber is open at13 above the inclined wall 20 so that refuse trucks can back up to thecombustion chamber and discharge their contents down the inclined wall20 on to the grate means GM, which is shown only schematically in FIG.10. A second embodiment having a restricted opening 201 formed betweendepending top bafiie 202 and inclined wall 20 is shown in FIG. 10. Theincinerator of FIG. may be charged by conveyor 203, or directly from atruck.

The walls 12 and 14 are continuous with portions 12a and 14a at theright hand end in FIGS. 1, 2 and 10 which continue into FIGS. 1A, 2A and10A to form a baffle chamber or secondary combustion chamber 207. Thebafiie or bridge wall 18:: shown in FIGS. 1 and 2 is an upward extensionof the rear wall 18 of the combustion chamber. The bridge wall may beforwardly inclined as shown in FIG. 10. Further downstream is adownwardly extending baflle or drop arch 22 shown in FIGS. 1A, 2A and10A, against which hot gases (about 1800 F.) impinge. Both the bridgewall and drop arch are upstream from the gas scrubber GS. The chamber207 may be provided with a sloping floor 24 which continues as at 24::in FIGS. 1A and 2A to form a floor for the gas scrubber GS. Optionally,the gas scrubber floor 24a may be separate as shown in FIG. 10A. Thechamber space defined between the bridge wall and scrubber inletdownstream of the drop arch is the second high temperature zone. In anincinerator utilizing the scrubber-dryer of this invention this zonedoes not act as a settling chamber. Prior art settling chambers,ordinarily of size 12 feet wide by 27 feet high by 35 feet long for a2-cell incinerator, can be eliminated in my invention since thescrubber-dryer can handle all the fly ash without preliminary settlingof large ash.

The floor 24a, sidewalls 12b and a top wall 14b which is an extension ofthe top wall 14a provide a gas scrubber chamber. The details of oneembodiment are shown in FIGS. 1A and 2A. In this chamber a series ofvertical piers 28 constitute scrubber elements which, as shown in FIGS.1A and 10A are arranged in rows and staggered relative to each other insuccessive rows to provide a tortuous path for the products ofcombustion and fly ash passing through the gas scrubber GS. These piersare spaced so that the area between them for the flow of combustiongases is reduced to about one-third the area within the baflle chamber12a, 14a, 24, so that the velocity of combustion gases and fly ashthrough the gas scrubber is increased for efiiciency of the gasscrubbing operation as will hereinafter appear.

The gas scrubber GS also includes a water distributing manifold 30adapted to be kept filled with water and having a slot 32 so that acurtain 34 of water falls therefrom as illustrated in FIGS. 1A, 2A and10A when there is no flow of combustion gases through the gas scrubber.This curtain is broken up for an important reason which will hereinafterappear during operation of my incinerator.

An alternative embodiment of the scrubber is shown in FIGS. 10A and 11.As with the embodiment of FIG. 1A, the V-shaped scrubber chambercontains four rows of staggered scrubber elements. The chamber walls asseen in FIG. 11 diverge from front to back (the downstream direction),and may be, for instance between about 1 /2 to 2 times wider at thedownstream end than at the upstream inlet end. The gap between adjacentimpingement piers or scrubber elements, in the direction transverse tothe direction of gases flow, in the first row is typically about 12inches. In each subsequent row downstream the gap decreases, beingtypically 8 inches, 6 inches and for the last, or wringer row 3 inches,respectively. Thus the number of pillars is increased in each downstreamrow. A typical pillar is 12 inches in diameter and about 8 feet high;there is no space above or below the pillars for the gases to bypassthereby escaping scrubbing. The rows of pillars may be uniformly spacedin the downstream direction,

having for example a 9 inch gap between each row. Compared to prior artdevices, the scrubber is very short; from the inlet end adjacent thebridge wall 204 as seen in FIG. 10A to the drop arch 205 the scrubber istypically about 9 feet long, but may be shorter or longer asrequirements dictate.

The products of combustion, after leaving the gas scrubber GS, enter aplenum chamber 36 shown in FIGS. 2A, 10A and 11, and flow upwardlythrough the drying chamber DC, first passing through the deflecting ordrying arch DA. The deflecting arch in the embodiment shown in FIG. 2Acomprises a horizontal wall 38 of concrete, castable ceramic, or thelike having reinforcing elements 40 therein and having a series ofinclined passages 42 which serve to deflect the gases of combustiontoward the sidewalls of the drying chamber DC. The drying chamber mayhave a vertical height approximately the same as shown for the plenumchamber 36 (portions having been broken away to conserve space on thedrawing). At the top of the drying chamber DC, a blower 44 is providedsuitably driven as by an electric motor 46. The blower has an intakechamber 48 and a discharge chamber or stack 50 to atmosphere.

In an alternate embodiment shown in FIGS. 10A and 11, the deflectingarch is inclined from the horizontal with perpendicular holes therein toachieve the function of directing the gases against the drying chamberwalls. In the drying chamber DC, water with fly ash entrained thereinthat has not been removed in the scrubber is wrung out or stripped fromthe gases by impingement against the sidewalls. The gases then passthrough a pair of second, optional, deflecting arches 206 disposed inchambers 48, 48' on each side of stack 50. At this stage, little or nowater will be wrung out, but some residual fly ash fines may stick tothe walls by impingement thereon. The gases then pass out stack 50 viatwo fans 44 which are typically rated at 3 times the amount of airneeded for combustion. The stack can be relatively short, and thusinexpensive, as compared to natural draft stacks, and is typically lessthan about 40 feet high.

As disclosed and claimed in the aforesaid copending divisionalapplication, the grate means GM comprises perforated grates 52 and ameans to support them so that they are reciprocably mounted. Thesegrates may be formed of cast iron or the like with small holes drilledtherethrough as shown in FIG. 1, and as shown in FIGS. 2, 5, 6 and 9 thegrates rest on grate carriers 54 which are supported by a frame Work oflateral and longitudinal I-beams 56 and 58, respectively. The I-beams 58are supported by rollers 60 which in turn are journalled in stationarybrackets on a partition 62 as shown in FIGS. 5 and 9 and a pair ofshoulders 64 of the combustion chamber sidewalls 12.

The framework 56, 58 also carries five rows of rollers 68 to supportlongitudinal channels 66 which are secured at 70 to the front wall 16 asshown in FIG. 2 so that the framework can reciprocate beneath thechannels but at the same time will support them. Surmounting thechannels 66 are inverted channels 72 having side edges which are groovedas shown in FIG. 5 to coact with end flanges 74 of the grates 52 toeffect a satisfactory seal for combustion purposes between the channels72 and the grates. The inverted channels 72 have ratchet-likeprojections 76 having an important function for the burning refuse aswill be described later. Recip'rocations are imparted to the grate meansGM by reciprocating the frame 56, 58 which has attached thereto threeracks 78 as shown in FIGS. 2 and 9 meshing with pinions 80 on a shaft82. A chain 84 operatively connects the shaft 82 to the output of aspeed reducer 86 driven by a motor 88. The motor is under control of aprojection 83 (shown in FIG. 1) which coacts with a pair of limitswitches 85 and 87 to energize the motor for rotation in alternatelyopposite directions in a manner well known in the art, thusautomatically reciprocating the grate means GM as long as current issupplied to the motor and controlled by the limit switches.

For supplying combustion air to the combustion chamber CC above thegrate GM, blowers 90 are provided as shown in FIGS. 1 and driven bymotors 91 and supplying air to manifolds 92 extending along thesidewalls 12. A plurality of nozzles 94 extend from each manifold 92into Venturi tubes 96 arranged at angles such as shown in order tofurnish air for combustion in a direction downwardly from the side Walls12 and toward the center of the grate means GM.

Additional combustion air is supplied by a blower 98 driven by a motor'100 and discharging into a duct 102 having discharge openings 104 and106 on opposite sides of the partition 62 as shown in FIG. 5 forsupplying combination air beneath the grate means GM. The grate means isinclined to facilitate the movement of burning refuse therealong towardthe dry ash conveyor AC and to effect a more even spreading and levelingout of the refuse and to effect distribution of combustion air throughthe grates 52 to the refuse. The downhill ends of the projections 76 areperforated as shown at 77 in FIGS. 5 and 6 to keep them relatively cooland promote mort complete combustion of the refuse.

As will hereinafter appear, water containing fly ash flows downwardlyalong the inclined bottom wall 24a of the gas scrubber as shown in FIG.2A and A into a trough 108. Discharge openings 110 lead therefrom into asludge conveyor trough 112 containing the sludge conveyor SC (not shownin FIG. 10A). The trough 112 as shown in FIG. 3 and dotted in FIG. 2Aleads to a sump 114 from which the water is pumped by a pump 116 drivenby a motor 118, the intake of the pump being shown at 120. The trough112 and the sump 114 thus constitute an open L-shaped settling tank fromwhich water is drawn for recirculation to the gas scrubber. The pump andmotor are contained in a compartment 122 sealed off from the tank 112,114 and the pump has an outlet pipe 124 leading to the manifold 30. Abaffle 126 serves as an aid to prevent the flow of sludge from thebottom of the trough 112 and the sump 114 into the intake 120.

In order to keep the water in the trough 112 and the sump 114 at apredetermined level 113 such as best shown in FIG. 2A, a water supplyline 128 flows through a water meter 130 to a float valve 132 in a floatchamber 134. The float chamber 134 has an outlet 136 leading into thesump 114. This arrangement provides make-up water to compensate for thatwhich is evaporated by operation of the incinerator. In actual practiceI find that a high water recovery is possible thus requiring only anominal amount of make-up water and effecting a substantial economy inthe use of water.

The ash conveyor AC as shown in FIG. 2 is adapted to receive dry ashesfalling off the lower (right hand) end of the grate means GM which itwill be noted is inclined downwardly toward the ash conveyor. Themarginal right hand end of the grate means reciprocates as indicated bydot-and-dash lines over the ash conveyor so as to discharge ashesdirectly into the conveyor. As noted in FIG. 1, the major area of thegrate means GM is provided with the perforated grates 52 whereas theleft hand end under the inclined wall and the right hand marginal endare provided with imperforate members 138 so that the burning of refuseis accomplished between the discharge end of the inclined wall 20 andthe imperforate members 138 at the downhill end of the grate means. Theimperforate members 138 just mentioned serve as a platform for theadvance of ashes from the grates 52 and into the ash conveyor AC. Asshown in FIG. 7, the ash conveyor at the right hand end has an upwardlyand outwardly inclined portion 139 extending from the combustion chamberto discharge in an ash box 140 or the like and is driven by a chain 142from the output shaft of a speed reducer 144 driven by a motor 146.

The sludge conveyor SC is somewhat similar in vertical cross section tothe ash conveyor AC shown in FIG. 7,

8 being driven by a chain 148 (FIG. 3) from a speed reducer 150 which inturn is driven by an electric motor 152. The sludge conveyor dischargesinto a sludge box 154 or the sludge may be otherwise disposed of.

In the operation of my refuse incinerator, a truck load of refuse isdumped into the open end 13 of the combustion chamber CC and slides downthe inclined wall 20 on to the imperforate members 138. Since aconsiderable portion of normal household and industrial waste andsimilar refuse consists of paper and other combustible materials, it canbe readily ignited, and after suitable ignition, the blowers 44, and 98may have their motors energized for operation. The motor 88 may also beenergized for reciprocating the grate means GM and the motors 146 and152 may be energized for operating the ash conveyor AC and the sludgeconveyor SC. The grate means GM is so designed as to hold and disturbthe refuse for efficient aeration which results in faster and morecomplete burning when compared to burning on stationary grates.

The burning refuse produces products of combustion including fly ash anddry ashes. The dry ashes are gradually deposited in the ash conveyor ACdue to the reciprocations of the grate means GM. The dry ashes arecarried by the ash conveyor AC up the inclined portion 139 of theconveyor and into the ash box or are otherwise disposed of.

Refuse is advanced along the grate means GM by reason of positionalchanges of the refuse relative to the grate accomplished during thebackward portion of reciprocating grate motion. During the forwardportion of grate motion a clear area of grate 138 becomes exposed fromunder the inclined wall 20 and is thereupon covered with incomingrefuse. Accordingly as grate motion reverses the refuse now becomespositionally held by the inclined wall 20 while the grate slips beneaththe refuse thereby effecting a change of position relative to the grate.The retarding effect of the inclined wall 20 is imparted through therefuse to all the burning material on the grate means, but notproportionally so. Heavier parts of the conglomerate refuse slip on thegrate less due to greater friction, and lighter parts thereby flowaround and past the heavier parts. Advancement of refuse along the grateis maintained as long as incoming refuse is suflicient- 1y present onthe inclined wall 20 to cover the free area exposed during forward gratemotion.

Large variations in the rate of burning are inherent in the particledisorder of accumulated refuse with its varied physical geometry andmaterial chemistry. It is to this situation that my grate isparticularly adaptable. As refuse moves onto the grate, ignition of therefuse occurs on the inclined wall 20 due to kindling from slower movingparts of preceding quantities. The selectivity of movement to variousparticle weights becomes increasingly defined while movement progresses.As advancement of the burning particles continues, rates of burning areequated by combustion to changes in density to which the grate means isselective and thereby translates to rates of movement. The accuracy oftranslation is evidenced by a line of demarcation that defines the inertma terial toward the discharge end of the grate. In essence, rates ofburning become rates of movement, and in such manner variables in theincineration of refuse are accommodated by the grate means as hereindisclosed.

The foregoing described operation has the effect of breaking down theindividual batches of refuse and substantially evenly distributing themover the grate means. Additional batches of refuse can be periodicallyfed to the incinerator to keep it in continuous operation. A majorfunction of the projections 76 is to lift and disturb portions of theload during forward grate motion for more eflFective aeration andconsequent burning.

The products of combustion including fly ash pass upwardly and over thebaflle or bridge wall 18:: as indi cated by arrows in FIG. 2 and underthe baflle 22 of FIG.

2A to the gas scrubber GS. The temperature generated in the combustionchamber may run as high as 1600 F. to 1800 F. and the velocity of theproducts of combustion and fly ash from the outlet end of the combustionchamber may be in the range of 1000 f.p.m. to 3000 f.p.m. caused by theoperation of the blowers 44, 90 and 98. Such high velocity is desirablein order to effectively wet the surfaces of the piers 28 with water fromthe curtain of water 34 which, of course, is distorted from the showingin FIG. 2A when the blowers are in operation. I have found that thewater effectively wets the surfaces of the piers 28 so most of the flyash will be collected in the water that gravitates downwardly along thepiers and flows downhill along the gas scrubber chamber floor 24a andinto the trough 108. The water also has the effect of keeping the piers28 cool relative to the transit gases of combustion by thermal sinklosses and vaporization of the water.

As noted above, the second high temperature zone 207 between the bridgewall 18a and the inlet of the scrubber permits some secondarycombustion, but is not a settling chamber. In prior art settlingchambers the gases speed was on the order of 1-9 feet/ second, the slowspeed permitting ash to settle out. However, in the present invention, asettling chamber per se may be omitted because of the high efliciency ofthe scrubber and dryer. In the second zone 207, the gases speed is above9 feet/ second, and may be as high as 30-40 feet/second. In moistclimates, the speed may be as low as 10-12 feet/ second; in the Mid-Westthe value may be 18-26 feet/ second and in more arid climates may beabout 30 feet/second. In all areas the speed depends on the moisturecontent of the refuse.

The size of the second high temperature area or chamber 207 is ininverse proportion to the gases speed: smaller for higher gases speed.In contrast to prior art, secondary chambers which operate as settlingchambers and which are typically three times larger than the primarycombustion chambers, the chamber 207 of my invention is typicallysmaller, and may be as little as /3 the combustion chamber CC size, foran equal capacity incinerator.

The spacing between the piers is such as to reduce the area throughwhich the products of combustion pass as they flow through the gasscrubber so that an even higher velocity is attained in the gas scrubber(on the order of 3000 to 9000 f.p.m.). Due to the increase in velocityof the products of combustion through the gas scrubber, as well as thepresence of water therein as films on the piers 28 and the coolingeffect of the water as it evaporates, the temperature is only about 200to 250 F. around the piers. The piers themselves do not get above about212 F. in normal operation. The velocity is then reduced again in thedrying chamber DC so that the temperature is increased to about 300-400"F. thus increasing the drying effect and making for a gas scrubber andgas dryer combination having a high overall efliciency.

By staggering the piers as shown in FIGS. 1A and 11, the flow past thefirst row impinges the second row and the flow past the second rowimpinges the third row and so on, in such manner as to effectivelyaccomplish maximum collection of fly ash. These piers are formedpreferably of water-resistant ceramic capable of withstanding hightemperature on the order encountered in the gas scrubber and towithstand the abrasive effect of the fly ash impinging against them. Apreferred pier material is a castable refractory having high strength,low iron content and good abrasion resistance. A commercially availabletype is AR-153 Castable made by Walsh Refrac tory Co. of St. Louis.Concrete will work for a short period of time but it is not preferred; acastable refractory has an estimated lifetime of 3-5 years. To increasepier strength and abrasion resistance, up to 50% by weight alumina canbe added to the castable refractory.

Although I do not wish to be bound by theory, it is important that thepiers have a high water retention characteristic, i.e., relativelysurface porous, and have a high abrasion resistance characteristic. Theporous impingement scrubber piers absorb water from the surfaceinwardly, and the surfaces are kept continuously wetted. Thus the waterevaporates to form steam from the action of hot gases and the piers areprotected by the collar of steam thus formed, by the evaporation, and bythe absorbed water.

As for the arrangement of the piers 28 in rows in the gas scrubber GS,the first row of piers has as one effect, the reduction of thetemperature of the products of combustion. The second row, being offsetrelative to the piers of the first row, collects fly ash impinging ontheir water films so as to be entrained in the water that gravitatesdownwardly along the piers. Likewise the third and fourth rows, beingoffset also collect ash. The piers obviously act as retarders for theproducts of combustion to effect separation of fly ash therefrom. Thethird row serves, inter alia, as a final wash for the removal of most ofthe residual fly ash from the first and second row, and the fourth rowacts as an impingement wringer. By the time the products of combustionpass the fourth row, up to of the fly ash has been removed. Slugs ofwater from the curtainn 34 act as lubricant for the fly ash thusreducing wear on the piers.

As compared to prior art spray chambers, the scrubber of this inventionoperates far more efliciently and effectively because the gases must actagainst the continuous discharge of the curtain of water. Prior artspray nozzles break up water into very fine droplets or mist-likeparticles, which evaporate in the gases in molecular form. This isparticularly true in incinerators having high gases temperatures. Butthe evaporated water cannot trap the fly ash and thus unacceptablelevels of dust and ash pass out the stack. Although I do not wish to bebound by theory, in my invention the gases impinge on the curtain ofwater and force it against the scrubber piers. In impinging on thecurtain, the ash entrained in the gases is trapped by the water andretained in relatively large droplets until they impinge on the piers.It is principally at the piers that the water is broken up into finedroplets leaving the ash to be washed down the pier faces by the excesswater, and pass along the floor into trough 108. Thus, the gases losekinetic energy by impingement against the water curtain. The rate ofheat exchange is relatively low and the droplets large. Since thedistance between the curtain and piers is small, on the order of 2-3feet, and the gases velocity large, the drops with the captive ash donot have time to evaporate before being immediately impacted against thepiers. Sprays of water cool the gases, but do not efliectively trap orretain the ash. In my invention the weight of the water is used toadvantage.

Because of the effectiveness of the water curtain and its relationshipto the piers in trapping and retaining products entrained in the gasesas compared to sprays, the scrubber can be used to advantage in lowtemperature operations such as removal of industrial vapors from exhaustgases, the trapping of S0 in the production of sulfuric acid, and thelike. Where desired, the scrubber and dryer of my invention can be usedwith a conventional incinerator having a settling chamber.

The relatively clean products of combustion and some water entrainedtherewith are discharged from the gas scrubber GS into the plenumchamber 36 which acts as a breaching or expansion chamber. The gasesthen flow upwardly through the deflection arch DA and into the dryingchamber DC. The passageways 42 of the deflection arch, being inclined asthey are, direct the products and water towards the walls of the dryingchamber as illustrated by arrows in FIG. 2A and the impingement of thewater against these walls results in a drying action by reason of suchwater trickling down the Walls of the plenum chamber and eventually intothe trough 108. Accordingly, products of combustion almost entirely freeof fly ash are discharged into the inlet 48 and through the 1 1 blower44 and its outlet 50 to atmosphere thus producing a clean burning refuseincinerator satisfactory for the requirements of most smoke ordinances.In the embodiment of FIGS. 10A and 11 there are a plurality ofimpingement walls 208, 209, 210, 211, and 212.

The fly ash and water draining from the gas scrubber into the trough 108drains through the discharge openings 110 into the sludge conveyortrough 112 and the sludge settles to the bottom of the trough whereby itmay be picked up by the lower stretch of blades of the sludge conveyorSC and pushed along the trough 112 toward the right and then up theinclined portion 139 and into the sludge box 154. Excess water drainsback into the trough 112 and finds its way into the sump 114 where thewater can be recirculated to the manifold 30 and the slot 32 to effectan economy of operation represented by a considerable saving of water asdistinguished from those types of gas scrubbers which use fresh waterthroughout their operation without recirculation. Some of the water,however, will evaporate because of the heat generated in the incineratorand this is automatically compensated for by operation of the floatvalve 132 which may be set to replenish the water to the level 113 shownin FIG. 2A. About 80 g.p.m. are added with an estimated loss of 15g.p.m. to the wet sludge. The estimated remainder of 65 g.p.m. isexhausted as water vapor from the stack.

The following examples will illustrate one or more of the severalembodiments of this invention.

Example 1.Prir art For comparative purposes, this example describes aconventional incinerator operation. The incinerator of this example hastwo cells or primary combustion chambers rated to operate at a total of400 tons per day. Each of the two side-by-side cells is on the order ofabout 9 /2 feet wide by 10 feet high and some 33 feet long. The twocells open at the downstream end into a fiy ash setting chamber which ison the order of 12 feet wide by 27 feet high and 35 feet long, with thelong axis of this settling chamber being set transverse to the long axisof the two side-by-side cells. This chamber also operates as a secondarycombustion zone or flame space. The downstream side of the settlingchamber, near an offset end, opens, into a dual-zone ash removalchamber. In this chamber there is a first dry zone that is about 12 feetwide by 15 feet high and 10 feet long where more ash settles out. Fromthe first dry zone the gases and fly ash thence pass through a cathedralwall or archway and proceed into a wet zone. This zone is a spraychamber 12 feet wide, 15 feet high and 18 feet long having recessedceiling and wall sprays. These operate to give both vertical andhorizontal sprays of water at the rate of about 100 gallons per minuteto remove some fly ash. From the spray chamber, the gases pass via ashort passageway into a 150 foot smoke stack. Pieces of charred paperthe size of the palm of a hand were exhausted from the stack, and thusthe output of the smoke stack was quantitatively estimated at being wellabove the permissible dust loading as defined above, 0.85 lbs. of dustper 1000 lbs. of flue gas. Although the two-cell plant was rated at 400tons/day, it operated Well below that value, at an estimated 300 to 350tons/ day. In addition to the disadvantages of dust loading, the charredpaper, and the large and expensive stack, both the ceiling and the wallsprayers, although they were recessed, continuously burned out andbecame clogged.

Example 1A .Prior art To improve the capacity of the above type ofincinerator, a conventional Schneible dual-silo collector was installedto take part of the load from the incinerator. A model F21C Multi-WashCollector made by the Schneible Company of Detroit, Mich, was attachedvia suitable duct work to the settling chamber of the incineratordescribed in Example 1. Such a conventional Schneible collector operatesby introducing, under force draft, dust, fumes or vapors tangentiallythrough an inlet at the bottom of the silo. The conical bottom creates avortex which sends the air upwards in a spiralling motion. A washingagent is introduced at no head pressure just below the entrainmentseparator and the water cascades downwardly evenly over plates carryingcollected material to the slurry outlet. The basic Schneible silo costsabout $70,000 including $6,500 for an associated settling tank; some ofthat cost was for concrete foundations. In addition, over 40 feet ofduct work costing atbout $11,000 and a fan costing about $10,000 wasrequired. This installation also required a separate stack, 32 feet highThe use of the Schneible multi-wash collectors, operating simultaneouslyin parallel with the original dual-zone ash removal chamber describedabove in Example 1, raised the capacity to about 450500 tons/ day whenoperating. However, the permissible duct loading of 0.85 lbs. of dustper 1000 lbs. of flue gas was not achieved, it being estimated that thedust loading was well in excess of that permissible figure. As with theoriginal dual-zone ash removal chamber of the incinerator describedabove in Example 1, the output from the Schneible stack included charredpieces of paper the size of the palm of ones hand.

In addition, the metal Schneible units had an extremely short life-timebecause of the acids formed during the washing of the incineratorcombustion product gases and the abrasion of parts. The silos were eatenand abraded through within five weeks and the unit leaked in numerousplaces. The entire unit was shut down about 50% of the time for repairsand cleaning. Each time the unit was shut down, the plant capacitydropped back to the original below-rated level. Hydrated lime in thewash water was tried but the amounts necessary for neutralization wasprohibitively expensive and caused severe clogging. Within 9 months, ofwhich the unit was down half that, the unit became unrepairable. Of theoriginal total cost of $89,000 about $60,000 was unrecoverable, andrepresents the cost (but not the operating and repair expenses) of theunit that operated unsatisfactorily for only about 4 /2 months effectivelife.

Example 2 The Schneible unit of Example 1A was replaced with anembodiment of the scrubber and dryer of the present invention. As withthe Schneible collector, this unit operated in parallel with thespray-type scrubber of the original plant. The fan and 32 foot stack ofthe Schneible device was salvaged and coupled to the scrubber and dryingchamber of the present invention, substantially that shown in theembodiment of FIGS. 1A, 2A and 3. The output of the two-celledincinerator plant above described rose to from 550 to 600 tons/day. Thiswas an improvement of from 250-300 tons/day over the original actualoutput of the plant, and an increase of 100150 tons/ day over the outputshown in Example 1A, where the Schneible collectors were used inconjunction with the original plant having the spray chamber. It wasestimated that about of the entire plant output was taken through thescrubber-dryer of this invention. It was observed that the dust loadingof the discharge from the stack connected to the scrubber-dryer of thisinvention appeared to be below the permissible level, and there was nolarge pieces of fly ash exhausting therefrom. No hydrated lime for acidneutralization was required, and no frequent downtime, with an attendantloss of capacity, for cleaning and repair was necessary.

Example 3 This illustrates the operation of an entire incinerator plantutilizing the V-shaped chamber scrubber substantially as shown in theembodiment of FIGS. 10A and 11 and having a dryer as shown in FIG. 2A.The plant is rated at 300 tons/day and consists of two 150 ton/daycells. The refuse, after being weighed, is received at the plant at adumping area and is pushed onto an inclined pan conveyor which feeds theincinerator units as shown in FIG. 10. The refuse falls by gravity downthe short inclined refractory hearth 20 onto a reciprocating gratesystem such as is disclosed and claimed in my copending divisionalapplication Ser. No. 648,845, filed Nov. 9, 1967. The combustion chamberCC is equipped with overfire air nozzles for the introduction ofsecondary combustion air. A force draft fan is provided for eachfurnace. The combustion gases pass from the furnace over a bridge walland below a drop curtain at relatively high velocities into thesecondary high temperature zone which operates as a secondary combustionzone, but no ash settling takes place. Then the gases enter the scrubbersystem of this invention. The scrubber system is that described abovewith reference to FIGS. A and 11. Water is recirculated at the rate of500 gallons/min, with make-up water being introduced at 80 gallons/ min.The curtain of water is formed by a slot opening across the full widthof the inlet to the scrubber section. The water depth in the roof troughis enough to insure a 1 to 2 inch deep continuous water flow into theslot. The cleaned gases pass into the expansion or dewatering sectionand thence through the deflection arch to impinge on the walls of thedrying chamber. This section further serves as an entrainment separatorpreceding the induced draft fan with the gases being taken off above theWater. Constant speed ID fans serve' each incinerator unit withadjustable dampers serving as air induction openings in the ID inletplenum to regulate the furnace draft. The fans discharge into a plenumsection which serves as the bottom inlet of the refractory lined steelstack. The gases are discharged from the stack approximately 32-35 feetabove the grade area at the rear of the plant.

Emission tests were conducted at this plant and were performed inaccordance with the requirements of the A.S.M.E. Test Codes PTC 21-1941Dust Separating Apparatus, and PTC 27-l957 Determining The DustConcentration in a Gas Stream, and the Informative Report No. 2 of theAir Pollution Control Association Incinerator Committee titled TestMethods for Determining Emission Characteristics of Incinerators by F.R. Rehm. Pursuant to the 3 codes and the study, the tests were carriedout to satisfy the four basic requirements, which are:

(1) Securing a truly representative sample of the gases and suspensoids;

(2) Filtering and weighing the particulates in the sample gas stream;

(3) Measuring the sampled gas volume;

(4) Making other supplementary measurements of temperature, pressure,gas density, gas comsumption, gas molecular weight, excess air levels,needed to compute dust loading.

In addition to the dust loading tests, volumetric determinations wereconducted on each unit. The visual appearance and the odorous nature ofthe stack effluents were regularly assessed throughout each dust loadingtest run. As part of the dust loading test, a continuous check was madeof the excess air levels of the exhaust efiluents. The sampledparticulates from the dust loading test were subjected to laboratoryanalyses. With the stack velocities encountered at this plant on the dayof testing, it can be anticipated that the maximum cumulative test error(sampling, weighing, volumetric, etc.) would approach plus or minus 9%Every precaution and effort was made to minimize any unnecessary testerror.

The results of the stack dust loading emission rates are summarized inTable I below and are presented on the basis of commonly used dustloading limitations. This table presents the results on an actual gasbasis. Runs 1-3 were on the No. 1 Incinerator cell; Runs 4-6 on the No.2 cell.

TABLE L-STACK EXIT DUST LOADINGS (ACTUAL) Corrected to 12% Corrected to50% C01 basis excess air basis Lbs. Lbs. dust/1,000 dust/1,000 Test RunGrains/ft." No. Gas Grains/it. 0. Gas

*SCTP132 F., 29.92 in. Hg.

The following Table II summarizes the test results expressed on the lesscommonly used dry standard cubic foot per minute basis. Standardconditions are sometimes defined as 32 F. and 29.92 in. Hg, andsometimes as 60 F. and 29.92 in. Hg.

TABLE Ill-STACK EXIT DUST LOADINGS (DRY) Corrected to 12% CO1 Correctedto 50% Excess Air Test Run Grains/dry it. Grains/dry It. Grains/dry th t*SCTP: 32 F., 29.92 in. Hg. TSCTP: 60 F., 29.92 in. Hg.

The above table shows that the performance of the No. 2 incinerator unitconsistently conformed to the requirement of 0.20 grain/dry standardcubic foot (defined at either 32 F. or 60 F.), corrected to a 50% excessair basis, which has been incorporated in a number of the more recentlyenacted air pollution ordinances. The last two test runs on the No. 1incinerator unit met this same requirement (60 F.) within the inherenterror of the test determination.

The average exit fiue gas dust loading of the three tests run on the N0.1 incinerator cell, while burning a residential or domestic refuse at,or in excess of, rated burning capacity and with scrubber water rates asoutlined above was 0.396 lb. dust/1000 lbs. flue gas, corrected to a 50%excess air basis. This average exit dust loading is below the commonlyused exit fiue gas dust loading limitation of 0.85 lb. dust/1000 lbs.flue gas, corrected to a 50% excess air basis. This data shows that theNo. 1 incinerator cell exhibited very good particulate emissionperformance.

The average exit flue gas dust loading of the three tests run on the No.2 incinerator cell while operating at rated burning capacity burningvarious combinations of commercial and domestic refuse and with scrubberwater rates as detailed above was 0.272 lb. dust/ 1000 lbs. flue gas,corrected to a 50% excess air basis. This average exit dust loading is0.85-0.272 XIOO-GSDZ,

below the commonly used exit fine gas dust loading limitation of 0.85lb. dust/1000 lbs. flue gas corrected to a 50% excess air basis. Thisdata shows the No. 2 incinerator cell also has excellent particulateemission performance.

The following Table HI was developed utilizing the dust loading testresults reported above for cell No. 2, and additional volumetric data inaccordance with the tests, including accurate weighing of the refusecharge, as follows:

TABLE IIL-STACK MASS EMISSION RATE Lbs/ton of Test run IncineratorLbs/min. Lbs/hour Charge 1 Visual emissions The Ringelmann Chartpublished by the U.S. Bureau of Mines is the most usually acceptedstandard upon which visual smoke emission limitations are based. TheRingelmann Chart consists of a series of cross-hatched black lines ofvarious widths printed on a white back ground. The lines are to beviewed at a distance sufficiently far to give a blended gray color withthe white background. Ringelmann numbers range from No. 0.0R for acompletely white smoke or visual discharge to a No. 5.0R density for asolid black emission. A No. 1.0R would be a dense black smoke, a No.2.0R a 40% dense black smoke, etc. The Ringelmann Chart has been printedonly on a black and white basis with gradations being various shades ofgray. To describe visual emissions that are other colors or shades, anopacity measuring device or scheme was devised. The opacity of a visualemission is related to the ability to see throng the visual plume and israted on an equivalent Ringelmann Number basis. All visual readings ofstack efiiuents suffer from various influences such as the differencebetween individuals eyesight, the viewing location, the backgroundagainst which the plume is assessed, the thickness of the plume, etc.Despite the vagaries in assigning a Ringelmann Number of an equivalentRingelmann Number to visual emissions, this is the method used almostexclusively in all air pollution control ordinances to measurepermissible emission levels. Practically all air pollution controlordinances make provision for some period of emission of No. 2.0Ringelmann smoke. Most air pollution ordinances prohibit visualemissions greater than No. 2.0 Ringelmann density except for certainoperating conditions for which limited amounts of such emissions arepermitted. The assessment of visual emissions having a relatively highmoisture content must be done carefully since it is at best a difficultdetermination.

The visual stack emission readings were recorded at regular intervalsthroughout each dust loading test run. The results of the visualemission observations are summarized in Table IV below:

TABLE IV.VISUAL EMISSIONS, NUMBER OF READINGS, EQUIVALENT RIN GELMANNNUMBER 0.0 R 0.5 R 1.0 R 1.5 R 2.0 R 3.0 R 4.0 R 5.0 R

Test

l 10 see. each.

From the above table, it can be seen that only during Dust Test Run No.2 was smoke of an opacity or density as great as an equivalentRingelmann No. 2.0 observed. This visual emission performance is wellwithin the most stringent visual emission limitations being enforced inthis country today. On two occasions during Dust Test Run No. 2, visualemissions of 10 seconds durations of an opacity of Ringelmann No. 2.0were observed. In Dust Test Runs No. 1, No. 3, No. 4 and No. 5, novisual emissions were observed that were greater than a Ringelmann No.1.0 density. In Dust Test Run No. 6, one reading of 16 Ringelmann No.1.5 density was observed. It is clear from the above data that the aboveincinerator units do not present any visual smoke emission performanceproblems when operated at, or slightly in excess of rated burningcapacity.

It should be noted that with the water vapor content of the stack gases(12.35% to 17.38%), there was a dense white vapor plume formed as thiswater vapor condensed in the cool outside ambient air on these dates.This white vapor plume should not be confused with visual smokeemissions. The white water vapor plume forms approximately 10-20 feetabove the point of stack discharge. The exhaust gases can be seen to bevirtually clear below this point.

From the foregoing specification, it will be obvious that I haveprovided a refuse incinerator and a method of treating refuse whichaccomplish the objects set forth in the foregoing specification. Anincinerator is disclosed which does not need a high chimney to createdraft as in many installations where the chimney alone may cost as muchas $125,000. In many prior art refuse incinerators the cost of blowersis also high because they must withstand considerable abrasive action byfly ash whereas in my installation the blower 44 can be of a relativelyinexpensive type since the products of combustion passing therethroughare relatively free of fly ash.

My apparatus and method contribute to minimization of air pollution asthe output from my incinerator is about to cleaner than the output fromconventional chimney, caused, of course, by the removal of a greaterproportion of fly ash in the eflicient gas scrubber disclosed. As far ascomplete refuse incinerator systems of comparable size are concerned,those with stacks or chimneys may cost three times as much as aninstallation of the kind herein disclosed.

Some changes may be made in the construction and arrangement of theparts of my incinerator, and my method steps may be varied to someextent without departing from the real spirit and purpose of myinvention, and it is my intention to cover by my claims any modifiedforms of structure, use of mechanical equivalents or modification of themethod steps disclosed which may reasonably be included within theirscope.

I claim as my invention:

1. In an incinerator comprising a primary combustion chamber, asecondary combustion chamber and fly ash removal means, the improvementin said fly ash removal means which comprises:

means defining a scrubber chamber having an inlet and outlet,

means defining scrubber elements disposed in said chamber, said elementshaving a relatively porous surface adapted to absorb water therein,

means for supplying water to the top of said scrubber chamber inlet,

means for directing said water in the form of a continuous curtainacross the width of said chamber, said directing means being disposed atthe top of the inlet end of said chamber and immediately upstream fromsaid elements, whereby fly ash entrained in gaseous products ofcombustion impinge on and are trapped by said water and said water iscarried by said gaseous products of combustion downstream to immediatelyimpinge on said scrubber elements, means for producing a high velocityflow of gaseous products of combustion from said primary combustionchamber through said scrubber chamber, said flow means being disposed incommunication with said scrubber chamber outlet, and means for removingfrom said scrubber chamber the water draining from said scrubberelements and the fly ash entrained therewith.

2. An improved incinerator as in claim 1 which includes a drying chamberdisposed between said scrubber chamber and said flow producing means,said drying chamber comprising side walls and means for deflecting saidgaseous products and water carried thereby toward said side walls toforcibly impinge thereon, whereby said water and residual fly ashentrained therewith are separated therefrom before entering said flowproducing means, said means for deflecting comprising a passageway insaid drying chamber, and a cross wall therein at an angle to the path ofgas flow through said passageway and having passages therethrough.

3. An improved incinerator as in claim 2 wherein said passagestherethrou-gh are oriented substantially normal to the plane of saidcross wall,

4. An improved incinerator as in claim 2 wherein said water removingmeans includes a sludge conveyor having a horizontal portion disposed toreceive water and fly ash entrained therewith from said scrubberelements and from said drying chamber and being operable to removesludge from said water, and having an inclined portion to elevate thesludge above the level of the water and discharge it from theincinerator.

5. An improved incinerator as in claim 1 wherein said scrubber elementscomprise a plurality of staggered rows of castable refractoryimpingement piers oriented vertically and thereby substantially parallelto the flow of said curtain of water, said piers being also orientednormal to the path of flow of said products of combustion.

6. An improved incinerator as in claim 5 wherein said piers are arrangedin spaced rows across said scrubber chamber with the spacing in each rowless than the preceding upstream row.

7. An improved incinerator as in claim 6 wherein said piers are spacedand of such dimension that the area through which said gaseous productspass is reduced to about one'third the area of said scrubber chamber.

8. An improved incinerator as in claim 1 wherein said means forsupplying water includes means for recirculating water from saidremoving means to said inlet end of said scrubber, a manifold forreceiving said recirculated water, said manifold having a slottransverse of said scrubber inlet through which said Water falls, saidslot being disposed at said inlet immediately upstream of said scrubberelements, and float-controlled means for supplying make-up water tocompensate for vaporization of water during operation of said scrubber.

9. An improved incinerator as in claim 1 wherein said scrubber chamberwidens from inlet to outlet and said scrubber elements are arranged inrows crosswise of said scrubber chamber with a series of spaced scrubberelements in each row with the spacing in each row progressively reducedin a downstream direction 10. An improved incinerator as in claim 9wherein said scrubber elements comprise a plurality of staggered rows ofcastable refractory impingement piers, the number of piers in eachsucceeding downstream row increasing.

11. A scrubber suitable for removing entrained vaporous or particulatematerial from gases comprising:

means defining a scrubber chamber having an inlet and outlet, meansdefining scrubber elements disposed in said chamber, said elementshaving a relatively porous surface adapted to absorb water therein, andbeing arranged in a plurality of rows with a spaced series thereof ineach row and an increasing number of elements in successive rows, thespacing between elements in each row decreasing in successive rows,

means for supplying water to the top of said scrubber chamber inlet,

means for directing said water in the form of a continuous verticalcurtain across the width of said chamber and said scrubber elementsbeing vertical and thereby parallel to such curtain of water, saiddirecting means being disposed at the top of the inlet end of saidchamber and immediately upstream in said gases impinges on and istrapped by said water, and said water is carried by said gasesdownstream to immediately impinge on said scrubber elements,

means for producing a high velocity flow of gases through said scrubberchamber, said flow means being disposed in communication with saidscrubber chamber outlet, and

means for removing from said scrubber chamber the water draining fromsaid scrubber elements and the material entrained therewith.

12. A scrubber as in claim 11 which includes a drying chamber disposedbetween said scrubber chamber and said flow producing means, said dryingchamber comprising side walls and means for deflecting said gases andwater carried thereby toward said side walls to forcibly impingethereon, whereby said water and residual entrained material therewithare separated therefrom before entering said flow producing means.

13. A scrubber as in claim 11 wherein said scrubber elements comprise aplurality of staggered rows of castable refractory impingement piersoriented perpendicular to the path of flow of said products ofcombustion.

14. A scrubber as in claim 11 wherein said scrubber chamber increases inwidth downstream relative to the flow of gases therethrough.

15. A scrubber suitable for removing entrained vaporous or particulatematerial from gases comprising:

means defining a scrubber chamber having an inlet and outlet, meansdefining scrubber elements disposed in said chamber, said elementshaving a relatively porous surface whereby water is absorbed therein,means for supplying water to the top of said scrubber chamber inlet,means for directing said water in the form of a continuous curtainacross the width of said chamber, said directing means being disposed atthe top of the inlet end of said chamber and upstream from saidelements, whereby said material entrained in said gases impinges on andis trapped by said water, and said water is carried by said gasesdownstream to immediately impinge on said scrubber elements, means forproducing a high velocity flow of gases through said scrubber chamber,said flow means being disposed in communication with said scrubberchamber outlet, means for removing from said scrubber chamber waterdraining from said scrubber elements and the material entrainedtherewith, said scrubber including a drying chamber disposed betweensaid scrubber chamber and said flow producing means, said drying chambercomprising side walls and means for deflecting said gases and watercarried thereby towards said side walls to forcibly impinge thereon,whereby said water and residual entrained material therewith areseparated therefrom before entering said flow producing means, saidscrubber elements comprising a plurality of staggered rows of castablerefractory impingement piers oriented vertically and perpendicular tothe path of said products of combustion, and said means for supplyingwater including means for recirculating water from said removing meansto said inlet end of said scrubber, a manifold for receiving saidrecirculated water, said manifold having a slot transverse of saidscrubber inlet through which said water falls, said slot being disposedat said inlet upstream of said scrubber elements, and float-controlledmeans for supplying make-up water to compensate for vaporization ofwater during operation of said scrubber.

16. A method of removing particulate matter enfrom said elements,whereby said material entrained trained in gases flowing from anincinerator comprising forming a continuous curtain of Water, passingsaid gases at high velocity-into contact with said curtain whereby saidparticulate matter is trapped thereby and said water is carrieddownstream by said gases in relatively large droplets, substantiallyimmediately and progressively constricting the area of passage of saidgases and water droplets through a plurality of piers adapted to absorbwater whereby the velocity of said gases is increased and said dropletshaving particulate matter trapped therein are collected, deflecting saidgases whereby a substantial amount of water is removed therefrom,removing said Water having particulate matter trapped therein, anddischarging said gases as flue gases, whereby said discharged flue gasesare substantially free of particulate matter.

17. A method as in claim 16 wherein said gases are gaseous incineratorcombustion products having fly ash entrained therein as said particulatematter, and said flue gases are discharged sufiiciently free of fly ashto be below 0.85 lb. dust/1000 lbs. of flue gas based on 50% excess air.

18. A method as in claim 17 which includes the steps of removing fly ashin the form of sludge from said removed water, recirculating said waterto provide water for said curtain, and adding make-up water tocompensate for evaporation loss.

19. A method as in claim 17 wherein said gaseous incinerator combustionproducts prior to passing through said water curtain have a temperatureof up to about 1800 F. and a velocity of between about 1000 to 3000f.p.m., the amount of said restriction is such as to raise the velocityof said combustion products by about threefold, theamount of water insaid curtain is controlled to entrain up to about 95% of said fly ash insaid water and to reduce the temperature of said gaseous products duringsaid constricting step to below about 250 F., and the velocity of saidgaseous products is reduced and the temperature raised during saidsubsequent deflecting step.

References Cited UNITED STATES PATENTS 830,974 9/1906 Decarie. 2,691,42310/1954 McIlvaine 233 2,935,375 5/1960 Boucher 55-84 2,947,383 8/1960Schytil et al. 5590 3,090,179 5/1963 Powell 55233 3,332,214 7/1967Huppke 5590 3,334,470 8/1967 Huppke 5590 FOREIGN PATENTS 498,585 9/ 1954Italy.

REUBEN FRIEDMAN, Primary Examiner.

CHARLES N. HART, Assistant Examiner.

US. Cl. X.R. 55-259 g g UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3447z87 Dated June 3, 1969 Inventor(s) L. H.Andersen It is certified that error. app'ears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Figure 2A, element "14a" should read -14b-.

Column 4, line 36, "FIG. 1" should be :--FIG. 2-.

Column 14, line 5, "No. should be Lbs.

SIENED'ANI.

I EALED Atteat:

wart! M. Fletcher, Ir. I WILLIAM E. SGHUYIM, JR- Lmnng flomissionesorramu

